General teachings concerning electrochemical cells may be found, for example, in U.S. Pat. No. 5,209,994 and U.S. Pat. No. 5,458,997 assigned to the assignee of the present invention. Electrochemical cells have found particular application in the medical field for use with heart pacemakers and other medical devices. Conventional cells, typically include a container with an open top which is closed by means of a lid or cover welded to the container to form a housing for the cell. The container and the cover are of electrically conductive material and serve as a contact for either the anode or cathode of the cell, e.g., a cathode current collector if the cell is a case positive cell such as described in U.S. Pat. No. 5,209,994 or an anode contact if the cell is a case negative cell such as described in U.S. Pat. No. 5,458,997. Inside the container is an anode/cathode assembly for use with the respective case positive or case negative cells. Further, the housing contains a material such as cathode material or electrolyte which is in contact with the cathode/anode assembly and the housing. A chemical reaction in the cell results in a voltage differential to generate electrical current to power a medical device.
Generally, the cover closes the container of the housing so that the contents of the cell are sealed therein. The housing must, however, provide access to the interior of the cell for at least two purposes. First, a lead connected to the anode or cathode current collector within the cell must pass from the interior of the cell to the space exterior of the cell. Second, cathode material or electrolyte must be filled into the housing. Conventionally, to accomplish such objectives, two holes are typically defined in the cover of the housing and structures are attached to the cover in association with these holes. For example, a "feedthrough ferrule" is attached to the lid to accommodate the electrical lead and a "fillport" is attached to the lid to accommodate the filling of cathode material or electrolyte into the cell.
In prior cell arrangements, the cover is formed by a generally rectangular blank stamped from a sheet of electrically conductive material. During the stamping, two holes are stamped through the blank. The feedthrough ferrule and the fillport are formed of discrete parts that are then welded to the generally rectangular blank, each in registration with one of the holes in the blank. Generally, the discrete feedthrough ferrule is formed by a relatively complicated machined ferrule and the fillport is formed of a drawn tubular member or may also be machined.
Table 1 below lists several U.S. Patents that describe electrochemical cells having containers with covers or lids that accommodate an electrical lead that passes through the cover and/or that have a fillport for filling cathode material or electrolyte into the cell interior:
TABLE 1 ______________________________________ Prior Art Patents U.S. Pat. No. Inventor(s) Issue Date ______________________________________ 5,209,994 Blattenberger et al. May 11, 1993 5,104,755 Taylor et al. Apr. 14, 1992 5,173,375 Cretzmeyer et al. Dec. 22, 1992 5,306,581 Taylor et al. Apr. 26, 1994 5,439,760 Howard et al. Aug. 8, 1995 5,458,997 Crespi et al. Oct. 17, 1995 ______________________________________
All patents listed in Table 1 above and all patents listed elsewhere herein are hereby incorporated by reference in their respective entireties.
Additionally, Table 2 below presents materials describing the manufacturing process of metal injection molding and are hereby incorporated by reference herein in their respective entireties:
Table 2: Prior Art Materials Regarding Metal Injection Molding
Article, "Metal Molding Maestros," Injection Molding (August 1995).
Article, "Powder Injection Molding: Cross-Fertilization at PIM '95," Injection Molding (October 1995).
Article, "Powder Injection Molding Breaks New Ground," Plastics Technology (August 1994).
Book, Randall M. German, Powder Injection Molding, Metal Powder Industries Federation, Princeton, N.J. (1990).
Article, "Metal Injection Molding" by Richard Drewes, Product Design and Development (November 1994).
As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Embodiments, and claims set forth below, many of the devices and methods disclosed in Table 1 and Table 2 may be modified advantageously by using the teachings of the present invention.